Oracle Service Cloud (OSvC) updates typically require just 5 to 15 minutes of application downtime during the update cutover. That's because nearly all the database modifications required for update are completed in advance of the cutover on the production site. These changes are made at the time the upgrade site is created.

Once an upgrade site is created, the corresponding production site must update to the version of the upgrade site. It is not possible to update to a different version until the current update has been completed. The database changes made on the production site are specifically designed to update the site to a specific version of OSvC and cannot be reversed or altered.

Example:

1) An 18C upgrade site is created. The production site is now locked to 18C.

2) 18D becomes generally available during the update process.

3) A client requests changing the target version to 18D, however, Oracle advises them that it is not possible to update to a different version prior to updating to the locked version (18C).